Began to appear doubles topics with the same content.
The database entry with slug "topic1428" is only 1. And belongs forum, too, one "16"
How could appear I do not know.
But I have no topics and posts on moderation
Remove all topics, where the line will be specified "Invalid X frame". I need to look through all the topics and look for "Invalid X frame"? I understand correctly?
But there is no duplicated topic in admin panel. If I delete one duplicate topic, the other disappears too.